Poster Session - Abstract # 11

Electrochemical Evaluation of the Local Effects of Zn²⁺ Photo Release in the Zebrafish Brain

Piyanka Hettiarachchi¹, Isabel Solowiej^1,2, Shawn C Burdette³, Michael A. Johnson¹

¹Department of Chemistry and R.N. Adams Institute for Bioanalytical Chemistry, University of Kansas, Lawrence, Kansas, USA; ²Department of Chemistry, Ohio Wesleyan University, Delaware, Ohio, USA; ³Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA, USA

Free, ionic zinc (Zn²⁺), an endogenous transition metal plays an important role in numerous intra- and extracellular functions in the central nervous system.  A large body of evidence suggests that imbalances in the Zn²⁺ homeostasis are associated with Parkinson’s disease (PD) which is a devastating neurodegenerative motor disorder characterized by dopaminergic neuron loss and dysfunction.  However, the specific effects and underlying mechanisms of action of Zn²⁺ on dopamine release, which is critical for motor control in PD, are not well understood.  The challenge with unraveling these specific mechanisms is that the signaling events guiding these activities operate within a sub-s time scale and thus the measurements should be obtained within this time regime.  In this project, we’re using a promising approach that involves the photolysis of a newly developed caged Zn compound combined with fast scan cyclic voltammetry (FSCV) at carbon fiber microelectrodes.  The analytical methodologies were developed to determine the effects of the photo-activated release of Zn²⁺ from a custom synthesized molecular cage on the dopamine release/uptake in whole brain preparations of zebrafish (Danio rerio).

The harvested whole brains placed in a perfusion chamber received a constant flow of oxygenated artificial cerebrospinal fluid (aCSF) heated to 28˚C to maintain viability. The brain was perfused with a xanthone-based photocage, and the light was supplied from a mercury light source, filtered with a 280 nm high pass filter, and gated through a shutter that is under computer control and synchronized with the FSCV measurements.  The light application parameters such as duration and light-to-stim delay were systematically optimized.  Our results indicate the photo uncaging of caged Zn affects the dopamine release and reuptake in the zebrafish brains.  These findings will help to expand the current knowledge on how Zn²⁺ affects dopamine release/uptake and thereby to unravel new therapeutic pathways to treat motor and cognitive deficiencies in patients with neurodegenerative disorders associated with Zn imbalance.